BFM-decomp/docs/backlog.md

Backlog — automation near-misses for hand-finishing

Generated by tools/backlog.py render from .run/backlog.jsonl. These are functions the Phase-21 automation got close on but did NOT byte-match. The whole-binary byte-gate is the sole arbiter (G3/P9): byte-matches bank and are NOT listed here — only genuine near-misses/blockers are. Ranked by hand-session priority: reach (×N propagation leverage) → closeness (match_one mismatch count, lower = closer) → size. Each row's best_draft is the closest C the machine reached — resume from there.

Open near-misses: 5 · by status {'near': 4, 'failed': 1} · by class {'WALL-PROVED': 1, 'SCHED+REGALLOC': 1, 'FRAME+SCHED': 1, 'SCHED': 1, None: 1}

#	addr	reach	class	nins	status	closeness	where it stuck	best draft
1	func_80032A74	None	WALL-PROVED	422	near	1	T4b HAND PASS S84 (2026-09-06, Fable Max): PROVED at 1 by producer census. Residual = ONE reload-time slot at sp+0x48 (the u16 lhu draft is 422/422 with DIFF 22 = frame rows only; the s16 lh draft is DIFF 1 at idx 244 with the frame exact). The four post-parameter slot producers (reload1.c:658 ghost alter_reg / caller-save.c:249 area / reload1.c:879 invalid-equiv address / reload1.c:3499 spill_stack_slot) each refuted on the bytes: the site loads lhu and the function has no lb and no double load (combine newi2pat ghosts re-derive a narrow load); no register-only insn shares a block with a call (no sched.c:4962 staleness, so no save area without sw/lw); no unallocated single-block equiv pseudo; $t0 holds no pseudo (else $t1 would be the spill reg) and LO mult results retry into GR_REGS. NEW mechanism measured: optimize_reg_copy_2 ghosts (tmp = x; tmp op= c; x = tmp) are minted AFTER regclass -> GR_REGS, allocated, vars=0 (P14). 18 isolated reproducers, 0 draft variants; cookbook §501-M; notes .run/P32/t4c/func_80032A74/NOTES.md	.run/P32/t4/drafts/func_80032A74_tuclean.c
2	func_800CF408	None	SCHED+REGALLOC	178	near	3	S83 Fable: 49 -> 3, zero pins (the §501-H shape + a dead arg1 kill against cse re-association + the P_TAG OT write + a named mhi born before block 1). Residual idx 10-12 = §501-H verbatim (the unboosted tag load blocks one cycle behind the tpage sw; the empty cycle eats the highest-LUID floater ori $s5,0x96) COUPLED to the $t2/$t3 qty_compare contest (2389 vs 2400): every cure of one re-opens the other. NEXT: fill the OT-chain lhu gap with an UNBOOSTED p & m24 as the target does (needs a 2-set a3 that combine does not re-merge — combine.c:2309 decrements reg_n_sets on the merge — e.g. a second set through a different width/mode or a volatile-qualified temp), or move the contest margin by one ref elsewhere (an extra ob use in a block that does not touch the tag load)	.run/P32/t5x/fable/func_800CF408.c
3	func_80039308	None	FRAME+SCHED	518	near	4	S83 Fable: 17 -> 4 in the real TU. Closed the 11-row alias block (natural spelling; tail via a pointer so the li follows the addu in RTL) and rows 390/391 (p = r + a dead reset). Residual 4 = two causes: rows 49/50 the hoisted constant 2 vs the pinned vbase preheader order (move_movables splices after source preheader code); rows 412/415 a PHANTOM 8-byte frame slot with no traffic at sp+8 between the arg1 HImode spill (sp+0) and cnt (sp+0x10) — lhu $s7 is reload's spill register; storing arg1 directly reproduces sh $a1/lhu $s7 but not the slot (frame 0x38 vs 0x40). NEXT: induce the phantom slot — a hard-reg spill_stack_slot (reload1.c spill_hard_reg on LO or $s7 during retry_global_alloc), cf. §501-E (pins forbid regs at retry) and the func_80032A74 ghost-pseudo finding (a stranded combine temp -> alter_reg 8-byte slot in regno order)	.run/P32/t5x/fable/func_80039308.c
4	func_80185810	None	SCHED	489	near	13	S83 Fable: 35 -> 13 at exact length; 3 of 4 windows closed (P_TAG bitfield OT link + integer add for the addu operand order; sched1 flush_pending_lists at the 33rd memory op explains the load order -> HI temps; hard-reg destinations are not birthing-boosted -> pins uu $4 / mode $5 / ot16 $6 give the LUID order; shf pin $3). Residual ONE cause idx 363-380: cl &= 0xFFFF is an unboosted 2nd set — the fence after p[7]/= is needed (else its two reads float to the block head, 43/51) yet it blocks sched2 fillers crossing into the tpage/code window. NEXT: a spelling in which cl is single-set (its high half cleared at birth: cl = (u16)... or the shift form) so no fence is needed, or the two cl reads consume a fresh single-set copy that combine cannot fold (nonzero_bits defeats a plain andi copy; try a subreg/HI-mode temp)	.run/P32/t5x/fable/func_80185810.c
5	func_80062144	None		None	failed		won't compile standalone (loose-typing / missing decl)